Application of Apple By-Products and Xanthan Gum in the Development of Fiber-Enriched Gluten-Free Muffins

The growing demand for gluten-free bakery products requires the development of formulations that overcome their typical technological and nutritional limitations. Using fruit by-products as natural fiber sources, in combination with xanthan gum (XG), supports a sustainable ingredient strategy that improves gluten-free product quality. This study investigated the effect of apple pomace (AP) (5% and 10%) and XG (1%) on the technological properties, texture profile, nutritional composition, and sensory acceptance of gluten-free muffins. Six formulations were prepared by partially replacing maize flour with AP and/or adding XG. AP (5–10%) reduced muffin height and volume compared with the control, whereas 1% XG increased muffin height by 11.16% and raised volume and specific volume by 38.46% and 36.11%, respectively. XG significantly decreased hardness compared with the control, while the effect of AP on texture was concentration-dependent: 5% AP reduced hardness, whereas 10% AP did not further improve softness. Combined use of AP and XG resulted in complementary effects, improving structural properties while increasing dietary fiber content. The muffins supplemented with AP were acceptable, and their overall acceptability did not differ significantly among the tested formulations. Overall, the results demonstrate that incorporating AP together with XG enhances both the technological and nutritional quality of gluten-free muffins, supporting the valorization of fruit-processing by-products in functional bakery applications.